Rough idle: Codes, Causes & Fixes

P0174 Powertrain The cylinder bank without cylinder 1 is running lean even with the maximum fuel correction… Moderate P0300 Powertrain The engine computer sees misfires that jump between cylinders or hit several cylinders at once. High P0101 Powertrain The MAF sensor's airflow reading doesn't match what the engine computer expects… Low P0171 Powertrain The engine computer is adding the maximum extra fuel it's allowed on bank 1 and still sees… Moderate P0172 Powertrain The engine computer is pulling as much fuel as it's allowed on bank 1 and the mixture is still… Moderate P0302 Powertrain Cylinder 2 keeps misfiring. On inline engines it's a middle cylinder, so rule out coolant… Moderate

P0008 Powertrain Camshaft timing on bank 1 has drifted from the crankshaft. Often a stretched timing chain. Moderate P0011 Powertrain The bank 1 intake cam sits further advanced than the PCM asked for, usually an oil or control… Moderate P0015 Powertrain The bank 1 exhaust cam sits later than commanded; a stretched chain or stuck exhaust phaser… Moderate P0016 Powertrain The bank 1 intake cam and the crankshaft are out of step, most often from a stretched or jumped… High P0017 Powertrain The bank 1 exhaust cam signal doesn't line up with the crankshaft; think chain, exhaust phaser… Moderate P0018 Powertrain The bank 2 intake cam is out of step with the crankshaft on a V or boxer engine; chain wear… High P0019 Powertrain The bank 2 exhaust cam signal doesn't match the crankshaft; chain, bank 2 exhaust phaser… Moderate P0021 Powertrain The bank 2 intake cam is more advanced than commanded or slow to respond; compare it with bank… Moderate P0024 Powertrain The bank 2 exhaust cam stays too far advanced or reacts too slowly; check the valve, the oil… Moderate P0068 Powertrain The airflow the engine measures doesn't match what the throttle opening says it should be. Moderate P0088 Powertrain Rail pressure is running well above the value the engine computer is commanding. Moderate P0089 Powertrain The fuel pressure regulator is getting its commands but pressure isn't responding the way it… Moderate P0102 Powertrain The MAF signal is too weak for the PCM to accept, so it treats the circuit as dead… Moderate P0105 Powertrain The PCM lost a usable signal from the manifold pressure sensor: dropouts, noise or values it… Moderate P0108 Powertrain The MAP signal is pinned near 5 volts, so the PCM sees impossibly high manifold pressure even… Moderate P0120 Powertrain The throttle position signal dropped out or glitched, so the PCM no longer trusts the throttle… Moderate P0121 Powertrain The throttle position reading is electrically valid but doesn't agree with engine load, airflow… Moderate P0132 Powertrain The upstream oxygen sensor on bank 1 reads too high: the engine is running rich or the signal… Moderate P0152 Powertrain Bank 2's front O2 sensor is pinned high – usually voltage leaking in from its heater wire… Moderate P0170 Powertrain Bank 1 fuel correction is far outside its normal window, lean or rich, and the ECU won't say… Moderate P0171 Powertrain The engine computer is adding the maximum extra fuel it's allowed on bank 1 and still sees… Moderate P0172 Powertrain The engine computer is pulling as much fuel as it's allowed on bank 1 and the mixture is still… Moderate P0173 Powertrain Fuel correction on bank 2, the side without cylinder 1, is out of range or unstable, lean… Moderate P0174 Powertrain The cylinder bank without cylinder 1 is running lean even with the maximum fuel correction… Moderate P0175 Powertrain Bank 2 is still running rich even though the PCM is already cutting fuel on that side as far as… Moderate P0191 Powertrain The rail pressure reading is electrically valid but doesn't make sense for how the engine… Moderate P0200 Powertrain The ECU found a fault in the injector control circuits that it can't pin on one cylinder, often… High P0201 Powertrain The ECU sees an open or faulty electrical circuit to injector 1, so cylinder 1 is probably… Moderate P0202 Powertrain Injector 2's circuit is open or out of range; on an inline-four it's a middle cylinder under… Moderate P0203 Powertrain The ECU sees no normal electrical response from injector 3: its coil, its wiring or its driver… Moderate